This invention relates to sheet handling systems and more particularly, to sheet reversing mechanisms. Prior art sheet reversing mechanisms such as in duplex copying and collating in electrostatographic printing machines often use a roller system for driving sheets to and from a reversing station. U.S. Pat. No. 4,054,285, assigned to the same assignee as the present invention, shows a roller system having a center drive roll engaging two sets of idler rolls. The center drive roll engages the first set of idler rolls to convey sheets into a bin and engages the second set of idler rolls to convey sheets away from the bin. The center drive roll simultaneously drives both sets of idler rolls at the same rate. A limitation with this mechanism is the inability to drive a sheet into and out of the bin at different rates. Therefore, it would be desirable to provide a sheet reversing mechanism in which sheets can be driven into a bin or reversing station at one rate and driven out of the reversing station at a different rate.
In sheet handling systems, it is often necessary to deskew or preregister a sheet before conveying to the next station. In prior art systems having two sets of idler rolls driven by the same drive rolls, it is not possible to stop movement of one set of idler rolls without stopping movement of the other set of idler rolls. Therefore, either an incoming or outgoing sheet cannot be stopped by the rolls for deskewing, preregistration or timing without stopping both the incoming and outgoing sheets. It would, therefore, be desirable to provide a sheet conveying system in which the rolls driving the incoming sheets are operable independent of the rolls driving the outgoing sheets.
There is often the problem of sheet jams in sheet handling systems as a result of a sheet conveyed between a pair of pinch rolls being carried around one of the rolls or a sheet will have insufficient beam strength to be suitably conveyed. This problem can be minimized by providing corrugations in the sheet as shown in British Pat. No. 1,439,268. However, the apparatus as described in British Pat. No. 1,439,268 is not applicable to sheet reversing systems. It would, therefore, be desirable to provide a sheet reversing mechanism having apparatus delivering corrugated sheets to an output station.
Accordingly, it is a primary object of this invention to provide an improved sheet reversing mechanism having independent control of the input and output sheets and providing easy to handle sheets at the output station.